Control arrangement for the male die of a hydraulic press brake

ABSTRACT

A control arrangement for maintaining the male die of a hydraulic press brake aligned in a predetermined relationship relative to its longitudinal axis during metal braking operations so as to compensate for variations in the resistance to being formed in the metal work piece to thereby maintain the male die properly aligned longitudinally and inhibit erratic bending of the metal work piece and possible die damage.

United States Patent Thatcher CONTROL ARRANGEMENT FOR THE MALE DIE OF A HYDRAULIC PRESS BRAKE w Russell S. Thatcher, Galveston, Tex.

Assignee: Kelso Marine, Inc., Galveston, Tex.

Filed: Nov. 12, 1970 Appl. No.: 88,531

Inventor:

U.S.Cl. ..60/97E,9l/17l,9l/4llR Int. Cl ..Fl5b 11/22 Field of Search ..60/97 E, 97 L; 91/171, 170 R, 91/411B,411R

References Cited UNITED STATES PATENTS Biggert ..60/97 E A5: Jla

[ 1 July 18,1972

2,759,330 8/1956 Van Broekhoven et a1 ..60/97 E 3,344,940 10/1967 Burgess et a1 ..91/171 X 3,448,577 6/1969 Crawford 3,509,721 5/1970 Crawford ..60/97 E X Primary Examiner-Edgar W. Geoghegan Attorney.lack W. Hayden [57] ABSTRACT A control arrangement for maintaining the male die of a hydraulic press brake aligned in a predetermined relationship relative to its longitudinal axis during metal braking operations so as to compensate for variations in the resistance to being formed in the metal work piece to thereby maintain the male die properly aligned longitudinally and inhibit erratic bending of the metal work piece and possible die damage.

6 Claim, 6 Drawing figures PATENTEU JUL! 8 m2 SHEET 1 OF 2 J w J E w Y B R 6 a F a, v

ATTORNEY PATENTEU JUL] 8 m2 SHEET 2 BF 2 \Q; L 3% L H v I 3% w 0 Q @o w 53 w o o o INVENTOR Jab W. Hagdew /l TTORNE Y CONTROL ARRANGEMENT FOR THE MALE DIE OF A HYDRAULIC PRESS BRAKE BACKGROUND OF THE INVENTION Hydraulic presses of the type for braking metal, that is, folding or bending metal plates, are generally constructed using two hydraulic cylinders to force a male die downward by means of a die holder. The die holder employed in present hydraulic presses available is of massive construction and is guided so as to guide the die into engagement with the metal work piece to be bent or formed.

As hydraulic presses become larger, that is, as they become capable of exerting greater force and/or applying force over a greater area, a point is reached where the die holder for the male die becomes so large that manufacturing and physical handling of the male die holder becomes extremely costly and impractical, particularly in those situations where long male dies are to be employed.

Also, unless the die holder has sufficient strength throughout its longitudinal extent, it will deflect upwardly under heavy loads, such deflection occurring more noticeably towards the center of the die holders span, and thereby resulting in improper die action during the forming operation of the metal.

While it might seem that the problem could be readily alleviated by using more than two hydraulic cylinders spaced in accordance with the stiffness requirement of the male die holder size and the required force to be employed in the metal braking operation, such is not the case as additional problems are encountered.

For example, since the force requirement, that is, the resistance to being formed along the length of the metal being bent, is not always uniform, that portion of the die encountering the greatest resistance does not continue to move downwardly with the rest of the die at the same velocity assuming identical fluid pressure to all of the hydraulic cylinders. In such situation, the straightness of the die is not maintained and erratic bending of the metal work piece occurs as well as possible damage to the die.

SUMMARY OF THE INVENTION The present invention overcomes these problems in providing a control arrangement for a male die holder wherein hydraulic fluid is metered to hydraulic cylinder and piston means which serves to raise and lower the die. The hydraulic fluid is metered to the hydraulic cylinder and piston means so that the same volume of oil enters each hydraulic cylinder and piston means during metal braking operations, and means are provided to vary the volume as may be required to any hydraulic cylinder and piston means as may be necessary to compensate for any variations in resistance in the metal work piece being formed and small differences in volume between each cylinder.

An object of the present invention is to provide a control arrangement for maintaining the male die of a hydraulic press brake aligned substantially parallel to its longitudinal axis throughout the longitudinal extent of the male die during metal braking operations.

Still another object of the present invention is to provide a hydraulic press brake which may be of any desired longitudinal extent and which includes means for maintaining the male die of the hydraulic press brake aligned in a predetermined manner relative to the longitudinal axis of the male die during metal braking operations to compensate for variations in resistance to being formed in the metal work piece to avoid erratic bending of the work piece and possible die damage.

Still another object of the present invention is to provide a male die holder of a hydraulic press brake which is formed of an I beam or wide flanged beam.

Yet a further object of the present invention is to provide a control arrangement for the male die holder and male die of a hydraulic press brake which maintains the die holder and male die properly aligned relative to a metal plate during metal braking operations while eliminating bulky, costly male die holder construction.

Still another object of the present invention is to provide a hydraulic press brake arrangement which eliminates the problems heretofore encountered with the die holder of a hydraulic press brake.

Still another object of the invention is to provide a control arrangement for effecting some misalignment of the male die relative to its longitudinal axis during metal braking operatrons.

Yet a further object of the present invention is to provide a control arrangement for a hydraulic press arrangement which enables a standard I or wide flanged beam to be employed as the die holder of the hydraulic press brake even in those in stances where the hydraulic press brake employs a male die of substantial longitudinal extent and wherein the hydraulic press brake is designed for a capacity of 1,000 to 10,000 tons or more.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram illustrating a form of the present invention;

FIG. 2 is a schematic diagram illustrating hydraulic cylinder and piston means diagrammatically connected with the die holder shown as being in the form of an I beam positioned above a metal work piece on a femaledie for forming thereof,

FIG. 3 is a schematic diagram illustrating an arrangement of an indicating means which may be employed in connection with the present invention for indicating variations of travel along the longitudinal extent of the male die holder and male die during metal braking operations;

FIG. 4 is a schematic diagram of the indicating means of FIG. 3 showing, for purposes of illustration only, one of many positions that the male die holder and male die may assume during metal braking operations;

FIG. 5 is a schematic diagram illustrating another position of the male die holder and male die that may be encountered during metal braking operations and which the present invention overcomes; and

FIG. 6 illustrates a control box for controlling the flow of the metered liquid in the hydraulic system of the present invention to compensate for the conditions that might occur in the male die and its holder during metal braking operations as illustrated in FIGS. 4 and 5 of the drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENT Attention is first directed to FIG. I of the drawings wherein a liquid reservoir is referred to generally by the numeral 10. Conduit means 11 communicates the reservoir 10 through pump means 12 and then to control valve means shown at 13. From the control valve, the liquid is conducted through conduit 14 to the positive liquid displacement means referred to generally at 15, four of which are shown. The positive liquid displacement means comprises positive displacement hydraulic motors of the gear, vane, or piston type which serves to divide the flow from the pump 12 into a plurality of streams of substantially equal liquid displacement.

The motors 16 comprising the positive displacement means 15 have their shafts ganged together or mutually connected in any suitable manner as represented by the dotted lines at 17 so that (by having their shafts mutually connected) one motor cannot move unless the other motors move the same angular distance.

For purposes of description only, the present invention will i It can be appreciated that a different number of hydraulic cylinder and piston means other than that specifically mentioned may be employed, and a different number of spaced groups of hydraulic cylinder and piston means arranged longitudinally of the male die holder and male die may be employed; however, each group will contain the same number of cylinders and the number of cylinders is divisible by the number of groups. For example, 16 hydraulic cylinder and piston means arranged longitudinally along the male die holder and male die could be divided into either two, four, or eight groups, with each group being arranged at spaced intervals longitudinally along the male die holder and male die.

In FIG. 1, the reference numeral 20 is employed to represent a single hydraulic cylinder and piston arrangement, and it also is employed to represent a group of four hydraulic cylinder and piston means as above described. It will also be noted that only the two hydraulic cylinder and piston means are shown in a completed hydraulic circuit; however, the two hydraulic cylinder and piston means 20 on the right-hand side of FIG. 1 should be connected in the same manner as those on the left-hand side to the separate streams eminating from the two positive displacement motor means shown on the righthand side in FIG. 1 as will be described.

The hydraulic cylinder and piston means includes a hydraulic male 21 in which is carried a piston 22 to which is connected a piston rod 23. The piston rod 23 is adapted to be connected at its lower end at 24 to a male die holder 25 on which the male die 26 is mounted.

As shown in FIG. 2 of the drawings, the amle die holder 25 may be in the form of an I beam, or it may be in the form of a wide flange beam. p The connection between the piston rod 23 and male die holder 25 may be of any suitable form and serves to raise and lower the male die 25 as will be described It will be noted that each of the streams of the plurality of streams which is formed by the positive liquid displacement means 15 is each separately communicated to a group of hydraulic cylinder and piston means 20, or to a separate hydraulic cylinder and piston 20. Since, for purposes of description, four hydraulic cylinder and piston means 20, or four groups of hydraulic cylinder an piston means 20 are schematically represented in FIG. 1, the positive displacement means will employ four pisitive displacement motors means l6positive 16b, 16c, and 160', respectively. Suitable conduit means as shown at 30, 31, 32, and 33 may be connected with the discharge side of each of the positive liquid displacement motor means 16a-16d, respectively, for receiving the stream therefrom. Each of such streams will be of substantially equal liquid displacement within the manufacturing tolerances of the motor means and conduit means. The conduit 30 is connected with the main shut off valve 35 through branch conduit 300; the conduit 31 is connected through the main shut off valve 36 through branch conduit 31a; and similarly a main shut off valve (not shown) is provided for each of conduits 32 and 33 in a manner as similarly shown and described with regard to conduits 30 and 31. As illustrated in the drawings, the main shut off valves 35 and 36 are in normally open position so that the liquid stream from each of the positive displacement motor means l6a-16d, respectively, may be separately communicated through its shut off valve and to hydraulic cylinder and piston means 20, or a group 20 of hydraulic cylinder and piston means communicated therewith. For example, the stream from positive displacement motor means 16a is discharged through conduit means 30, branch 30a, main shut off valve 35 and into the valve discharge conduit 37 into hydraulic cylinder and piston means 20a.

Similarly, the stream from motor means 16d is discharged through conduit meanS 31, branch 31a, main shut off valve 36, and into the valve discharge conduit 38 into hydraulic cylinder and piston means 20b. The details of the identical hydraulic circuits to hydraulic cylinder and piston means 20c and 20d are omitted but are represented at dotted lines 32a and 33a, respectively. Thus, each separate stream exerts a force on the top side of the piston 22 in each of the four hydraulic cylinder and piston means 20a, 20b, 20c, and 20d to thereby lower the male die holder 25 and male die 26.

As noted, the four hydraulic cylinder and piston means 20a-20 are arranged at generally equally spaced intervals longitudinally along the male die holder 25 and male die 26 to properly guide and lower the male die holder and male die during metal forming and braking operations.

Since the minor differences in liquid displacement and leakage of even so-called identical motor units 16 or hydraulic cylinder units 20 are too great for satisfactory performance when three or more metered fluid streams are employed in hydraulic press use, suitable means are provided for correcting any flow difierences in the plurality of separate liquid flow streams 16a-16d. Of course, additional positive displacement motors may be provided for supplying as many separate streams as may be required for each hydraulic cylinder and piston means 20, or for each group of hydraulic cylinder and piston means 20 as are employed in any situation. Correction for minor liquid leakage is accomplished with the by-pass valves 40 and 41 which are connected to communicate with the conduits 30 and 31 as shown in FIG. 1 of the drawings. Similar by-pass valves are provided for each of the other two liquid streams from motors 16c, 16d in the control arrangement, as illustrated.

A supplementary means to compensate for liquid flow differences in the systems may be accomplished by means of needle valve which communicates the conduit 30 around the by-pass valve means 40 to communicate with the conduit 52 connected on the discharge side of the by-pass valve means 40, which conduit means 52 in turn communicates with the common manifold 60. Needle valve 51 communicates conduit means 31 around by-pass valve means 41 and communicates with by-pass valve discharge conduit means 62 which in turn communicates with common manifold 60. A similar arrangement may be provided for each of the streams flowing from motor means 16c and 16d through conduits 32 and 33 to their respective hydraulic cylinder and piston means, or grouped hydraulic cylinder and piston means 200 and 20d, respectively, illustrated on the right-hand side of FIG. 1 in the drawings.

Since the liquid being discharged from each positive liquid displacement means 16a-16d is not identical in volume, it can be appreciated that all of the hydraulic cylinder and piston means 20a-20a' will not be moved downwardly at a uniform rate to lower the male die holder 25 and male die 26 to bend metal work piece 65 as illustrated in dotted line at 66 in FIG. 2

. of the drawings. By-pass valves 40, 41, etc., are therefore provided to shunt liquid as required to reduce the downward velocity of the male die and die holder when the indicator flags (FIGS. 3 and 4) indicate misalignment.

In fixed bottoming die arrangements shims can be utilized to enable some limited corrective action. In socalled air bend arrangements where the metal is not bottomed into the female die 100, as illustrated in FIG. 2, shimming can be effectively used to some extent to aid in correcting for spring back problems. However, such method is time consuming and costly.

At times differences in resistance in bending or forming of a metal plate along the length to be formed is caused by variation in metal hardness. Increases in local hardness cause greater metal spring back which in turn necessitates bending the metal farther than normally required. When this occurs, the separate liquid stream flowing through each of the conduits 30, 31, 32, and 33 to each of its hydraulic cylinder and piston means 20a-20d, respectively, may be bypassed by means of the by-pass valve means 40 to the common manifold 60 whereupon it is returned through the conduit 70 to be discharged into the reservoir 10 at 71. Thus, movement of any hydraulic cylinder and piston means 20, or group of hydraulic cylinder and piston means 20 may be slowed, or retarded relative to the others. This arrangement enables the male die holder 25 and male die 26 to move in a manner so that it may be misaligned sufficiently to compensate for hard or soft areas in the metal throughout the longitudinal extent of the male die during metal braking operations. The present invention may be employed either in a fixed bottoming die arrangement, where the metal work piece contacts the bottom of the die in its final bending operation, or it may be employed in an air bending arrangement, as illustrated in FIG. 2. Where the invention is employed with a fixed bottoming die arrangement, shims will be provided to compensate for the spring back action of the metal.

FIGS. 3 through 6 diagrammatically illustrate an arrangement for detecting and compensating for variations in die holder travel along its length. In FIG. 3, it will be noted that the male die holder an male die 26 are schematically represented at 80. For purposes of illustration, four groups of hydraulic cylinder and piston means are shown as being spaced longitudinally along the male die holder and male die 80, such groups being referred to by the numerals 81a, 81b, 81c, and 81d, and each group employing four hydraulic cylinder and piston means. Common manifolds 82a, 82b, 82c, and 82d are provided so as to communicate streams from 30, 31, 32, and 33 to the groups 81a, 81b, 81c, and 81d respectively.

Suitable indicating means are referred to generally at 85 are provided for indicating variations in travel of the male die and male die holder at spaced longitudinal intervals thereof. Indicating means 85 is shown in the drawings as including cable means 86a, 86b, 86c, and 86d, one of which is connected to the male die holder generally adjacent the central point 87 of each group of hydraulic cylinder and piston means 81a, 81b, 81c, and 81d, respectively as illustrated. Each cable is then passed over pulley means 88 and connected by means of a constant rate spring, or weight 91 which is in turn connected at its end 92 to the stationary wall 93. Each cable carries a colored flag or some index mark or means as represented at 95 so that variations in travel of the cables 86 may be readily detected as diagrammatically illustrated in FIG. 4.

It will be noted that each of the by-pass valve means 40 and 41 is shown in FIG. 1 as being solenoid actuated and as being connected by suitable electric leads 40a and 4012, respectively, to the control box or panel designated Sw in FIG. 6. The operator of the hydraulic press by visually noting any variation between the index marks or flags 95 on the cables 86a, 86b, 86c, and 86d, as illustrated in FIG. 4, immediately presses the buttons to open the appropriate by-pass valves and slow up any hydraulic cylinder and piston group or groups that are indicated as advancing more rapidly than the others. As illustrated, the group of hydraulic cylinder an piston means connected by common manifolds 82a, 82b with motor means 16a, and 16b, respectively, are moving ahead of those groups of hydraulic cylinder and piston means connected to receive separate liquid streams from motor means represented by 16c and 16d, respectively.

Therefore, by pressing the first two buttons 86a and 86b in the F row (for fast) of control box Sw, solenoid actuated bypass valve means 40 and 41 are actuated to bypass the liquid streams from motor means 16a and 16b therethrough and into common manifold 60 to be returned to liquid reservoir 10. Bypassing the liquid from any group or groups of hydraulic cylinder and piston means slows the travel of piston 22 and the piston rod 23 connected therewith which in turn slows travel of that portion of male die holder 25 and male die 26. Such action may be continued until all four index indicators 95 are in alignment.

When all index indicators are aligned, this indicates that the male die holder 25 and male die 26 are traveling downwardly in a manner so that it is parallel to its longitudinal axis, and there is no flexing or bending of the male die holder and male die along its longitudinal extent. When all of the index markers are aligned again as shown in FIG. 3, the operator removes his hand from the control button 86a and 86b on the control box Sw and all hydraulic cylinder and piston groups are supplied with liquid from their respective stream.

Similarly, by pressing down on buttons 86c and 86d in the S row (slow row), the operator in the above illustration could accomplish the same effect as described above. In other words, button 86a in row F and button 86d in S row are electronically connected to actuate the same solenoid valve; button 86b in F row and button 86c in S row are electrically connected to actuate the same solenoid valve; button 860 in F row and 86b in S row are electrically connected to actuate the same solenoid valve; and button 86d in F row and button 86a in S row are electrically connected to actuate the same solenoid valve. Regardless of which marker or combination or markers is out of line, they may be controlled in the manner as described.

It is appreciated that the solenoid actuated by-pass valves connected in the hydraulic circuit with each motor means 16a, 16b, 16c, and 16d is electrically connected with control box Sw in a manner well known in the art.

It can also be appreciated that the indicating means 85 with the markers 95 could have substituted therefor any of several electronic arrangements so that .any flexing of the male die holder 25 and male die 26 in an undesired manner could be transmitted to actuate the by-pass valve means to direct liquid away from any of the common manifolds 82a82d connected with each of the four groups.

While FIG. 4 illustrates the male die holder and male die in one position, it will be noted that FIG. 5 illustrates the male die holder 80 in still another possible longitudinal misalignment position during formation of the metal work piece 65 of FIG. 2. While only two possible positions of the die holder 25 and male die 26 are illustrated in FIGS. 4 and 5, it can be appreciated that any combination of irregularities may occur in the male die holder 25 and male die 26. However, by arranging the hydraulic cylinders and the indicating means at spaced intervals along the longitudinal extent of the male die holder 25 and male die 26 and by coupling the indicating means 85 with the control means Sw for actuating by-pass valve means associated with each stream so as to actuate the by-pass valves and direct liquid from the hydraulic cylinder means and piston means, the rate of movement of the male die holder 25 and male die 26 at longitudinally spaced intervals therealong may be controlled so as to maintain it substantially parallel to its longitudinal axis throughout its longitudinal extent to thereby accomplish the bending operation in a proper manner without damage to the die or the metal piece being worked.

Thus, the male die holder 25 and male die 26 of the present invention may be of any desired longitudinal extent to accomplish a desired result, yet control may be maintained throughout the longitudinal extent of the male die holder and male die to bend and form a metal work piece while reducing the possibility of damage to the male die and die holder. Also, such arrangement avoids the use of bulky, costly male die holders heretofore employed in hydraulic press brakes.

Each main shut off valve, such as at 35, 36, may be solenoid actuated to close the valve and shut off the liquid stream to any particular group or groups of hydraulic cylinder and piston means. Control valve means 13 is shown as being manually actuated; however, it also could be solenoid actuated if so desired. Each shut off valve as at 36, 35 is connected to discharge to the liquid reservoir 10 when in closed position, such arrangement being diagrammatically illustrated at 35a, 36a.

Thus, the control arrangement of the present invention may be employed to maintain the male die parallel to its longitudinal axis, or for misaligning the male die relative to its longitudinal axis to accomplish the desired metal braking operations.

The foregoing disclosure and description of the invention are illustrative and explanatory thereof, and various changes in the size, shape, and materials as well as in the details of the illustrated construction may be made without departing from the spirit of the invention.

What is claimed is:

l. A control arrangement for maintaining the male die of a hydraulic press brake aligned in a predetermined relationship relative to its longitudinal axis during metal braking operations comprising:

a. pump means for connecting with a liquid reservoir;

b. positive liquid displacement means for receiving the liquid flow from said pump means to divide the liquid flow into a plurality of streams os substantially equal liquid displacement;

c. a plurality of double acting hydraulic cylinder and piston means spaced longitudinally of the male die and each of said cylinder and piston means communicating with a separate stream from the plurality of streams;

d. piston rod means for connecting said piston means and the male die to raise and lower the male die;

e. indicating means associated with the male die at spaced intervals therealong indicating the vertical movement of the male die; and

f. by-pass valve means to selectively bypass the liquid stream from any of said hydraulic cylinder and piston means in an amount to maintain the male die aligned in a predetermined relationship to its longitudinal axis during metal braking operations.

2. The invention of claim 1 wherein said liquid displacement means comprises positive displacement hydraulic motors which are mutually connected so that all move the same angular distance.

3. The invention of claim 1 wherein said hydraulic cylinder and piston means comprises a plurality of groups of hydraulic cylinders and pistons spaced longitudinally of the male die with each of said groups containing the same number of hydraulic cylinders and pistons with the total number of hydraulic cylinders and pistons being divisible by the total number of groups.

4. The invention of claim 3 including a main shut ofi' valve between said positive liquid displacement means and each of said groups of hydraulic cylinder and piston means which may be actuated to shut ofi flow to the group of hydraluic cylinder and piston means with which the liquid flow through said main shut off valve communicates.

5. The invention of claim 1 wherein said hydraulic motors are reversible.

6. The invention of claim 1 including control valve means between said pump means and said liquid displacement means, and conduit means connected with said control valve means and said hydraulic cylinder and piston means whereby when said control valve means is shifted to communicate liquid from said pump means to said conduit means, said piston and piston rod means raises the male die.

" golf {X} RUSSELL S. THATCHER l; that error appears in the ia patent oeid Patent are hereby corrected as Column'3, line 25, change "male" to cylind er -g, I Column 3, line 30, change amle' to --male-- 'i i Column 3, line 32, after "beam", cancel 'Yp".. Z

Column 3, line 41, change "an" to .fl'ld'f.

Column 3, line 43, change "pisiti ve to positive-:.

Column 3, line 44, Change "l6positive" to l Signed and sealed this 6th day .of March 1 973,

(SEAL) Attest:

EDWARD M.FLETCHER,JR. V 7 ROBERT' GOTTSCHALK Attesting Officer 1 1 Commissioner of Patents 

1. A control arrangement for maintaining the male die of a hydraulic press brake aligned in a predetermined relationship relative to its longitudinal axis during metal braking operations comprising: a. pump means for connecting with a liquid reservoir; b. positive liquid displacement means for receiving the liquid flow from said pump means to divide the liquid flow into a plurality of streams os substantially equal liquid displacement; c. a plurality of double acting hydraulic cylinder and piston means spaced longitudinally of the male die and each of said cylinder and piston means communicating with a separate stream from the plurality of streams; d. piston rod means for connecting said piston means and the male die to raise and lower the male die; e. indicating means associated with the male die at spaced intervals therealong indicating the vertical movement of the male die; and f. by-pass valve means to selectively bypass the liquid stream from any of said hydraulic cylinder and piston means in an amount to maintain the male die aligned in a predetermined relationship to its longitudinal axis during metal braking operations.
 2. The invention of claim 1 wherein said liquid displacement means comprises positive displacement hydraulic motors which are mutually connected so that all move the same angular distance.
 3. The invention of claim 1 wherein said hydraulic cylinder and piston means comprises a plurality of groups of hydraulic cylinders and pistons spaced longitudinally of the male die with each of said groups containing the same number of hydraulic cylinders and pistons with the total number of hydraulic cylinders and pistons being divisible by the total number of groups.
 4. The invention of claim 3 including a main shut off valve between said positive liquid displacement means and each of said groups of hydraulic cylinder and piston means which may be actuated to shut off flow to the group of hydraluic cylinder and piston means with which the liquid flow through said main shut off valve communicates.
 5. The invention of claim 1 wherein said hydraulic motors are reversible.
 6. The invention of claim 1 including control valve means between said pump means and said liquid displacement means, and conduit means connected with said control valve means and said hydraulic cylinder and piston means whereby when said control valve means is shifted to communicate liquid from said pump means to said conduit means, said piston and piston rod means raises the male die. 